Polymer electrolyte and manufacturing method therefor

Abstract

A polymer electrolyte and a method for manufacturing the same are disclosed. More specifically, a polymer electrolyte membrane having excellent ionic conductivity and low crosslinking degree can be prepared using a crosslinkable reversible addition fragmentation chain transfer polymerization agent (RAFT agent).

1 . A polymer electrolyte, comprising:
 a polymer comprising a monomer comprising ethylene oxide (EO) repeating units;   a reversible addition fragmentation chain transfer polymerization agent (RAFT agent) comprising styrene groups at respective ends thereof; and   a solvate ionic liquid (SIL) comprising (a) a lithium salt and (b) a glyme-based material or an amide-based material.   
     
     
         2 . The polymer electrolyte according to  claim 1 , wherein
 the polymer is present in an amount of 40% by weight to 60% by weight;   the RAFT agent is present in an amount of 3% by weight to 10% by weight; and   the SIL is present in an amount of 30% by weight to 50% by weight.   
     
     
         3 . The polymer electrolyte according to  claim 1 , wherein the monomer comprising the ethylene oxide repeating units is at least one selected from the group consisting of poly(ethylene glycol) methyl ether acrylate (PEGMEA) and poly(ethylene glycol) methyl ether methacrylate (PEGMEMA). 
     
     
         4 . The polymer electrolyte according to  claim 1 , wherein the RAFT agent comprises styrene functional group having C═C double bonds at respective ends thereof. 
     
     
         5 . The polymer electrolyte according to  claim 1 , wherein the RAFT agent is at least one selected from the group consisting of 3,4-divinylbenzyl trithiocarbonate (DVBTC) represented by Formula 1 and trithiocarbonate represented by Formula 2 below: 
       
         
           
           
               
               
           
         
       
     
     
         6 . The polymer electrolyte according to  claim 1 , wherein the RAFT agent is crosslinked with the polymer. 
     
     
         7 . The polymer electrolyte according to  claim 1 , wherein in the SIL, a molar ratio of the lithium salt and the glyme-based material is 1:0.1 to 3, or a molar ratio of the lithium salt and the amide-based material is 1:1 to 6. 
     
     
         8 . The polymer electrolyte according to  claim 7 , wherein the glyme-based material is at least one selected from the group consisting of monoglyme, diglyme, triglyme, and tetraglyme. 
     
     
         9 . The polymer electrolyte according to  claim 7 , wherein the amide-based material is at least one selected from the group consisting of N-methylacetamide (NMAC), acetamide, N-methylpropionamide, N-ethylacetamide, propionamide, formamide, N-methylformamide, N-ethylformamide, N,N-dimethylformamide, N,N-diethylformamide, N,N-dimethylacetamide, and N,N-diethylacetamide. 
     
     
         10 . The polymer electrolyte according to  claim 7 , wherein the lithium salt is at least one selected from the group consisting of LiSCN, LiN(CN) 2 , LiClO 4 , LiBF 4 , LiAsF 6 , LiPF 6 , LiCF 3 SO 3 , LiN(SO 2 F) 2 , Li(CF 3 SO 2 ) 3 C, LiN(SO 2 CF 3 ) 2 , LiN(SO 2 CF 2 CF 3 ) 2 , LiSbF 6 , LiPF 3 (C 2 F 5 ) 3 , LiPF 3 (CF 3 ) 3 , and LIB(C 2 O 4 ) 2 . 
     
     
         11 . The polymer electrolyte according to  claim 1 , wherein the SIL is impregnated inside a chain of the polymer or contained in a swollen form inside the chain of the polymer. 
     
     
         12 . The polymer electrolyte according to  claim 1 , wherein the polymer electrolyte is a polymer electrolyte membrane in a form of a network. 
     
     
         13 . A method for manufacturing a polymer electrolyte comprising the steps of:
 (S1) mixing   a monomer comprising ethylene oxide (EO) repeating units,   a reversible addition fragmentation chain transfer polymerization agent (RAFT agent),   a solvate ionic liquid (SIL) comprising (a) a lithium salt and (b) a glyme-based material or an amide-based material, and   an initiator,   to prepare a mixed solution;   (S2) removing oxygen from the mixed solution obtained in step (S1) above; and   (S3) applying the mixed solution, from which oxygen has been removed in step (S2) above, to a substrate and curing the result.   
     
     
         14 . The method for manufacturing the polymer electrolyte according to  claim 13 , wherein in step (S1), 40% by weight to 60% by weight of the monomer containing EO repeating units; 3% by weight to 10% by weight of the RAFT agent; 30% by weight to 50% by weight of the SIL; and 0.1% by weight to 1% by weight of the initiator are mixed. 
     
     
         15 . The method for manufacturing the polymer electrolyte according to  claim 13 , wherein in step (S3), the curing is thermal-curing or photo-curing. 
     
     
         16 . A lithium secondary battery comprising the polymer electrolyte of  claim 1 .